BKNZOIC ACID ^ 199
_____......._ _ .....w_.___________.___ .............._______________\__________________V X ^"^ £„.
crystallised by dissolving it in the smallest quantity of ether"and
then adding petroleum ether. ; •
The yield is theoretical. , ,;„
IIO.N "*" N.on.irci ^ N.OII
<x- or <f////-oxnne. /3- or ,s^v/-oxime.
Properties of the $-ftcnzaIdoxu)n\—Colourless needles, m. p.
Reaction,—Repeat the reaction for n-benzaldoxime. In this
case bcnxonitrile is formed, which separates in oily drops having
a characteristic smell. See Appendix^ p. 301.
I* KKl'AR AT/ION 90.
Benzole Acid, C0H6CO.OH
5 gnus. bcn/,yl chloride.
4 ,, anhydrous sodium carbonate (in 50 c.c. water).
8*5 „ potassium jKirmanganate (in 150 c.c. water).
The benzyl chloride and sodium carbonate solution arc mixed
in a round flask (| litre) attached to a reflux condenser, and
boiled gently over wire-gau/'ie, whilst the permanganate solution
is gradually dropped in from a tap-funnel pushed through the
top of the condenser. In the course of 2 — 3 hours the pink
colour of the permanganate will have vanished and been replaced
by a mass of dark brown precipitate of manganese dioxide.
When the liquid is cold, a stream of sulphur dioxide is passed in
until the manganese dioxide is dissolved (see p. 166). The
liquid is allowed to cool and the benxoic acid, which separates,
is filtered at the pump, washed with a little cold water and
recrystallised from hot water; m. p. 121°. The yield is
theoretical. The reaction probably occurs in two steps.
1. 2C,,Hf)CH.,Ci -f NaXO-j H- II..O -
2C(}Hr)CH,OH -1- 2NaCl + CO3.
2. 3C6H6CH2OI1 f- 4KMn<)4 -
3CnII:,COOK 4- 4MnO2 + KOH + 4H3O,